Weather presents a serious challenge to safety and mobility on our national system of roads and highways. Weather events, including winter storms, and even light rain or fog, can dramatically impact traffic flow and safety. The Federal Highway Administration (FHWA) seeks to address these weather-related transportation challenges through the provision of better information on the timing, location and extent of weather impacts, advanced warning of weather events, better integration of weather information into traffic operations, and the application of advanced tools to support decision making. One such tool is a Maintenance Decision Support System (MDSS), which offers guidance for maintenance managers and engineers by providing forecasts of weather and pavement conditions and generating recommendations on efficient maintenance treatment strategies. An MDSS offers unique capabilities in support of operational decision-making, pavement treatment, and resource deployment.
This report presents the results of a case study evaluation of the deployment of an MDSS in Maine. The MDSS was deployed by Maine Department of Transportation's (DOT) Scarborough crew on a segment of interstate in the vicinity of Portland, in support of winter maintenance operations during the winter of 2006-2007. This evaluation was conducted to understand the uses and benefits of an MDSS, as well as to examine institutional issues faced by MaineDOT’s Scarborough crew and to identify a set of lessons learned. The methodology involved a careful tracking of each of 12 winter storm events, coupled with a reconstruction of the crew’s decision processes and treatment actions throughout each event. The documentation of the event reconstruction included the maintenance of logs by the Scarborough crew as well as post-event telephone interviews with the crew and their supervisor.
The MDSS deployed by MaineDOT in the winter of 2006-2007 offered the DOT and the Scarborough crew a useful winter storm planning tool that supplemented other resources. MaineDOT found their experience overall with the MDSS to be a beneficial one. However, it was apparent from the event reconstruction and interviews with the crews that the influence of this tool on their maintenance and treatment conditions could have been greater had the crews perceived a greater degree of accuracy, reliability, and consistency in the forecasts and treatment recommendations provided. MaineDOT experienced an unusually mild winter, which presented a challenge for weather forecasting tools. Many weather events hovered between snow and rain, thus making it difficult for the MDSS (as well as other weather forecasting tools) to forecast precipitation type, amount, and timing with accuracy. An MDSS must seek to demonstrate accuracy and consistency across all storm types that a DOT might experience if it is to be a trusted tool of the maintenance crew. The following set of lessons learned is provided in support of ensuring a tool that will be perceived as accurate and reliable.
- Configure MDSS treatment recommendations in close consultation with the DOT, and customize them to fit the conditions, needs, and practices of the crews in the district where the MDSS will be used. In providing a treatment protocol for incorporation into an MDSS, MaineDOT decided to select an"average" set of treatment guidelines under a set of weather and pavement temperature ranges that could apply across the state. However, the Scarborough crew tends to apply more chemicals under a given set of weather and pavement conditions than the state average treatments that were configured in the MDSS, so throughout the assessment, the Scarborough crew tended to exceed the initial recommended treatment levels of the MDSS. In the judgment and experience of the Scarborough crew, the MDSS was under-recommending the amount of chemicals that were needed.
The state DOT should work closely with the MDSS vendor to implement a protocol of treatment recommendations that offer the potential for effectiveness and cost savings, consistent with the DOT’s standards for road maintenance. Arriving at an optimal configuration is likely to be an iterative process, with the vendor and the DOT working together to make adjustments, based on the performance of the MDSS after trial periods. The DOT may discover in this process that their existing treatment protocols can be modified to achieve greater efficiencies and savings.
- Select the alert topics and alert timing that will be most helpful in making road treatment decisions and to avoid generating too many alerts, which can be distracting The MDSS offered MaineDOT a wide variety of possible alerts covering all possible event types for each forecast point created for the study region. Across the 12 events reviewed in this evaluation, there was an average of 50 alerts per event and about 3.3 alerts per hour based on the criteria specified by MaineDOT. According to the Scarborough crew, this was such a large number of alerts that they found themselves disregarding many of them, and they indicated that at some points the large number of alerts was distracting. In MaineDOT's experience, alerts for each of the forecast points proved not to be necessary, since the multiple alerts often said the same thing. Alerts issued for different forecast points are only helpful when the information at each forecast point is significantly different from others. Other lessons learned regarding the alerts include:
- Configure forecast points that are outside the maintenance area along storm paths to offer improved advance warning of storms
- Create alert wording that is short and clear
- Configure the alerts according to the times of day when the crews are prepared to receive them and make the best use of them
- Provide a mechanism in MDSS treatment recommendations to incorporate the effectiveness of prior treatments, along with observational data, in order to better adjust forward looking recommendations. The MDSS used by MaineDOT was of most value at the front end of a storm. The Scarborough crew evaluated the MDSS before every storm event, along with their other sources of road weather information, and made their decisions whether to pre-treat the road and what type and amount of chemicals to apply. The MDSS was used less often during the course of a storm, in part due to the following reasons:
- The MDSS was not able to factor current conditions into its recommendations,
- Data on crew actions and resulting road conditions was not being integrated into the MDSS
- The crew was too busy fighting the storm to pay attention to the MDSS during the storm
Maintenance crews need concise, timely information mainly about variations in conditions across their region of responsibility and forecasts of changes in the timing and type of precipitation, air and pavement temperature trends, and guidance for optimal treatment types and amounts based in part on actions they already have taken. The supervisors as well were often not at their desks in front of their computers during storm events to monitor the MDSS. As a result, the Scarborough crew consistently consulted the MDSS before the event but not regularly during the event. DOTs can enhance the potential accuracy and benefit of an MDSS by making observational data from RWIS/ESS available for the geographic areas to be covered by the MDSS forecasts and treatment recommendations.
The MDSS deployed by MaineDOT raised awareness throughout the state of the value and potential of a tool that could supplement their existing road weather forecasting and management tools. However, to fully realize the benefits of an MDSS, the tool needs to be perceived as accurate and reliable by the maintenance crews. DOT agencies need to work closely with the MDSS vendors to ensure that the treatment recommendations offered by the MDSS are appropriately customized for their geographic and climactic environment and their operational needs. A more accurate and reliable tool will contribute to improved maintenance decision-making during weather events, resulting in increased safety, mobility and productivity.